Instrumentation to detect various physical parameters such as acceleration or force, pressure and temperature has long been in demand. The availability of fiber optic technology makes practical the use of transducers which respond to one or more such physical parameters to alter the transmission of light along an optical fiber path. This provides inexpensive remote sensing in hostile environments.
Transducers of this sort have been provided in the past and various examples of such senses are shown in U.S. Pat. Nos. 4,300,813, 4071,753, 3,731,542, 3,566,140, 3,463,931, 3,224,279 and 3,146,057. Such systems utilized multi-mode light transmission along optical fibers and are relatively simple to construct but of limited sensitivity. Due to the circular geometry of optical fibers used in such systems, they are also highly nonlinear in the transfer function which relates the parameter being sensed to the amount of variation in the light transmitted along the optical path and ultimately to the output of the system. Such transducers also are sensitive to motion in at least two orthogonal directions unless physical restraints, likely to impede sensitivity, are applied to restrict motion.